A technical system can comprise a plurality of different system components and/or subsystems. These subsystems can consist of software and/or hardware components. Each component in a subsystem can comprise functional components providing functions which can be activated by other components of the same or by another subsystem. The components of a subsystem can communicate with each other by means of a local communication network. A system, in particular a safety-critical system, can comprise embedded subsystems that communicate with each other and build up a larger loosely coupled system having a complex configuration.
The analysis by means of safety analysis data models of complex systems is in particular important during the development of a complex system. These safety analysis data models are provided for identifying possible drawbacks or insufficiencies of the systems, in particular in terms of system safety. Especially for complex technical systems, a response to a data input or data stimulus can vary depending on the current or momentary state of the respective system. For example, triggering an emergency brake of a transportation system in a stop mode has no effect whereas the effect is dramatically if the transportation system is in high speed operation.
For conventional fault tree analysis, data models exist that aim at a general analysis for a loss of function. Modular or compositional safety analysis methodologies such as component fault trees brake down the complexity of the safety-critical system. In industrial applications, development artefacts such as components or units are often reused from existing artefacts to save development time and development costs. Changes are made to these existing artefacts to match the requirements of the developed complex system. In software development, such a reuse strategy is also known as cone and own. When these development artefacts are reused, their existing safety analysis can form an important input for an early safety assessment of the developed system, since they already provide a valid data model. Complex components of the system that provide more than simple closed loop functionality may have different operational modes that can be active for different situations the complex system is in. In this case, the complexity of the system is not only expressed in the various number of components and their dependencies, but also in the modes the individual states the components are in for a specific situation of the complex system.